Bus fleet replacement optimization considering life-cycle carbon emissions and total cost of ownership

Abstract

To explore the benefits and potential of electricity and hydrogen as alternative fuels for regular buses, a mixed-integer planning model was constructed to determine the schedule optimization scheme for bus fleet replacement. The model was based on the comprehensive analysis of carbon emissions and the total cost of ownership from a life cycle perspective. Using actual operational data of buses powered by diesel, natural gas, hybrid, plug-in electric, and hydrogen fuel cells, the effects of uncertainty in the power mix, acquisition cost, hydrogen production, and hydrogen usage cost on the fleet replacement schedule were explored. The results reveal that plug-in electric buses are currently the optimal choice for bus fleet replacement. Given the current level of vehicle technology and hydrogen production, hydrogen fuel cell buses(HFCEBs)are advisable during bus fleet replacement. Until the production of blue or green hydrogen becomes commercially viable, promoting HFCEBs on a large scale by extending financial subsidies is not recommended. The proposed method can help authorities identify optimized bus fleet replacement options under specific constraints and desired objectives to promote green and sustainable development.

Keywords

bus fleet replacement / life-cycle carbon emissions / total cost of ownership / mixed-integer programming / alternative fuel / electric bus / hydrogen fuel cell bus

References

[1] Lu Y R, Guo X C, Li J C, et al.Tourist travel behavior in rural areas considering bus route preferences[J].Journal of Southeast University(English Edition), 2023, 39(1): 49-61. DOI: 10.3969/j.issn.1003-7985.
[2] Department for Transport(DfT). Annual bus statistics: England2020/21[EB/OL].(2021)[2022-06-25]. https://www.gov.uk/ government/statistics/annual-bus-statistics-year-ending-March-2021.
[3] Sui Y, Zhang H R, Shang W L, et al.Mining urban sustainable performance: Spatio-temporal emission potential changes of urban transit buses in post-COVID-19 future[J].Applied Energy, 2020, 280: 115966. DOI: 10.1016/j.apenergy.2020.115966.
[4] Chen L, Lin B L, Wang L, et al.Transfer of freight flow between highway and railway based on carbon emissions[J].Journal of Southeast University(Natural Science Edition), 2015, 45(5): 1002-1007. DOI:10.3969 /j.issn.1001-0505. (in Chinese)
[5] Meinrenken C J, Lackner K S.Fleet view of electrified transportation reveals smaller potential to reduce GHG emissions[J].Applied Energy, 2015, 138: 393-403. DOI: 10.1016/j.apenergy.2014.10.082.
[6] Ayetor G K, Mbonigaba I, Sunnu A K, et al.Impact of replacing ICE bus fleet with electric bus fleet in Africa: A lifetime assessment[J].Energy, 2021, 221: 119852. DOI: 10.1016/j.energy.2021.119852.
[7] Du H B, Kommalapati R R.Environmental sustainability of public transportation fleet replacement with electric buses in Houston: A megacity in the USA[J]. International Journal of Sustainable Engineering, 2021, 14(6): 1858-1870. DOI: 10.1080/19397038.2021.1972491.
[8] Islam A, Lownes N.When to go electric? A parallel bus fleet replacement study[J].Transportation Research Part D: Transport and Environment, 2019, 72: 299-311. DOI: 10.1016/j.trd.2019.05.007.
[9] Pelletier S, Jabali O, Mendoza J E, et al.The electric bus fleet transition problem[J].Transportation Research Part C: Emerging Technologies, 2019, 109: 174-193. DOI: 10.1016/j.trc.2019.10.012.
[10] Harris A, Soban D, Smyth B M, et al.A probabilistic fleet analysis for energy consumption, life cycle cost and greenhouse gas emissions modelling of bus technologies[J]. Applied Energy, 2020, 261: 114422. DOI: 10.1016/j.apenergy.2019.114422.
[11] Bo W, Ren H S, Geng W, et al.Investigation of the environmental impacts of steel deck pavement based on life cycle assessment[J]. Journal of Southeast University(English Edition), 2020, 36(3): 334-340. DOI: 10.3969/j.issn.1003-7985.
[12] López-Ibarra J A, Gaztañaga H, Saez-de-Ibarra A, et al. Plug-in hybrid electric buses total cost of ownership optimization at fleet level based on battery aging[J].Applied Energy, 2020, 280: 115887. DOI: 10.1016/j.apenergy.2020.115887.
[13] Lu C R, Xie D F, Zhao X M, et al.The role of alternative fuel buses in the transition period of public transport electrification in Europe: A lifecycle perspective[J]. International Journal of Sustainable Transportation, 2023, 17(6):626-638.DOI:10.1080/15568318.2022.2079445.
[14] Ajanovic A, Glatt A, Haas R.Prospects and impediments for hydrogen fuel cell buses[J].Energy, 2021, 235: 121340. DOI: 10.1016/j.energy.2021.121340.
[15] Cohan D S, Sengupta S.Net greenhouse gas emissions savings from natural gas substitutions in vehicles, furnaces, and power plants[J]. International Journal of Global Warming, 2016, 9: 254-273. DOI: 10.1504/ijgw.2016.074960.
[16] Han S M, Kim J H, Yoo S H.The public’s acceptance toward building a hydrogen fueling station near their residences: The case of South Korea[J]. International Journal of Hydrogen Energy, 2022, 47(7): 4284-4293. DOI: 10.1016/j.ijhydene.2021.11.106.
[17] Gustafsson M, Svensson N, Eklund M, et al.Well-to-wheel greenhouse gas emissions of heavy-duty transports: Influence of electricity carbon intensity[J]. Transportation Research Part D: Transport and Environment, 2021, 93: 102757. DOI: 10.1016/j.trd.2021.102757.
[18] Cullen D A, Neyerlin K C, Ahluwalia R K, et al.New roads and challenges for fuel cells in heavy-duty transportation[J].Nature Energy, 2021, 6: 462-474. DOI: 10.1038/s41560-021-00775-z.
[19] Pamucar D, Iordache M, Deveci M, et al. A new hybrid fuzzy multi-criteria decision methodology model for prioritizing the alternatives of the hydrogen bus development: A case study from Romania[J]. International Journal of Hydrogen Energy, 2021, 46:(57)29616-29637. DOI: 10.1016/j.ijhydene.2020.10.172.
[20] Gunawan T A, Williamson I, Raine D, et al.Decarbonising city bus networks in Ireland with renewable hydrogen[J].International Journal of Hydrogen Energy, 2021, 46(57):28870-28886.DOI:10.1016/j.ijhydene.2020.11.164.